Bicycles and other people powered vehicles are often equipped with variable speed transmissions in order to accomodate different riding conditions and the comfort of different riders. These transmissions are shifted to permit changes in wheel torque and gear ratios so that the operator of the vehicle may pedal at a pedal speed and torque which are most comfortable for that operator under the conditions he is currently encountering.
Although some people enjoy manually shifting such transmissions others do not and merely want to enjoy the pleasure of riding the vehicle and the exercise they receive without being bothered with gear shifting decisions and manipulations. Such people often shift improperly causing damage to the vehicle and a rough uncomfortable ride.
A variety of other automatic transmission shifters for bicycles and other vehicles have been suggested in the past. They have typically been mechanically, hydraulically or pneumatically operated devices. One such device is shown in U.S. Pat. No. 4,352,503 to Cotter.
Although such prior systems are simple, reliable and effective, they have a limited flexibility and provide only a small variety of operational features in their operating mode.
For example, bicycles are the most common people powered vehicles and a derailleur system for shifting the drive chain between multiple sprockets is the most popular type of transmission. They are manufactured in 3, 5, 10, 12 and 15 speed models which must be conventionally shifted by the rider. Automatic transmissions which have been designed in the past for such vehicles have not had the capability of conveniently displaying to the driver information indicating which sprockets are currently being used, they cannot automatically lock the transmission in low gear when the rider is riding uphill or provide a variety of other features which would be useful.